Signs of a malfunctioning coolant temperature sensor
In the modern world, almost every car is equipped with special devices for monitoring engine operation - antifreeze temperature sensors. On hot days they are simply necessary to maintain a constant engine temperature. Without a sensor, the engine will overheat or may stop altogether while driving.
Sensors in used cars are especially susceptible to damage. But sensors in relatively new cars can also be faulty. In both cases, a damaged sensor does not bring anything good. If a malfunction is not noticed in time, it can lead to various breakdowns and damage to the car.
What is DTOZH and its purpose?
First, it’s worth finding out what this device actually is.
The coolant temperature sensor (CTS) is a device that monitors and maintains the optimal mode of a car engine, thanks to which it quickly warms up.
The sensor is very small. And one might think that his role is as insignificant as his size. But in fact it is very important. It significantly affects not only the engine itself, but also the car as a whole. And if the sensor is faulty, it can cause many problems. Late intervention can speed up machine breakdown. Therefore, if this small sensor fails, then you cannot pull it.
Operating principle of the coolant temperature sensor
The sensor is located next to the thermostat. This arrangement ensures the highest accuracy of DTOZh signals. It also needs to come into contact with the coolant. Coolant, or antifreeze, absorbs the heat generated by the cylinders.
And the sensor detects this temperature change and sends signals to the electronic control unit. Using these signals, he can adjust the operation of the engine, as well as the composition of the fuel mixture.
When the sensor breaks down for some reason, fuel can be consumed very quickly, since the signals sent will be incorrect.
If there is not enough antifreeze, then the sensor will send incorrect signals. Therefore, you should periodically check the level of antifreeze in the cylinder blocks.
How to recognize signs of trouble
All machine devices break down sooner or later. And the sensor is no exception. It wears out easily and brings a lot of problems to the driver while driving.
A breakdown can be detected even during a routine inspection, but sometimes you have to resort to more serious measures. Usually this method is postponed because... Often a sensor malfunction is visible to the eye.
As a last resort, you can simply measure its resistance and voltage.
If the DTOZH is faulty, it causes problems such as:
- increased fuel consumption
- increased carbon dioxide emissions into the environment
- engine shutdown
- poor car handling
- slow warming up of the car
- engine heating
Sometimes the sensor's performance is affected by old wiring, rust, or poor assembly. But the sensor itself may be unharmed. But in most cases, the sensor itself is broken. Therefore, you cannot delay replacing it.
Replacing the sensor
The car begins to act up and stall. What is the problem? The first thing that comes to mind is a faulty engine. Replacing the engine with a new one may not solve the problem. Sometimes simply replacing the sensor will resolve the problem. With this replacement you can protect your car from further damage.
Conclusion
Any driver can notice signs of a faulty DTOZh with the naked eye. The main thing is to take the right measures to replace or repair it. But it is best not to skimp and purchase a new sensor that will ensure a safe and enjoyable driving experience without any problems.
Source: http://avto-kuplya.ru/tekhnicheskie-voprosy/proverka-okhlozhdeniya/34-priznaki-neispravnosti-datchika-temperatury-okhlazhdayushchej-zhidkosti
Let's look at the signs of a malfunctioning coolant temperature sensor
Signs of a malfunction of the coolant temperature sensor are often present in cars that have been “running on the roads” for many thousands of kilometers; in new cars, such defects are also quite common.
Modern cars, without exception, are equipped with reliable devices that successfully monitor engine parameters online. These devices are especially relevant during the hot summer, when the risk of overheating the car engine, as well as the temperature of the antifreeze, increases. If such a device fails, there is a risk of engine overheating.
Operating principle of DTOZH
DTOZH, what is it ? The temperature sensor, which cools the engine, monitors the optimal engine mode. DTOZH also shows system malfunction - this is a necessary condition to avoid overheating.
The sensor also needs to be in contact with a cooling fluid, which takes on the excess heat generated by the engine. If any violations occur, it detects temperature fluctuations and sends impulses to the control unit.
Thanks to such impulses, it is possible to adjust both the operation of the engine and the consistency of the combustible mixture entering it. If this small but extremely important device breaks down, fuel enters the engine uncontrollably and the signal received at the driver's control panel will be distorted, showing signs of a faulty coolant temperature sensor.
If there is a shortage of antifreeze, the device will also begin to function with errors; therefore, it is necessary to regularly monitor the amount of antifreeze in the cylinders.
The size of the device is small and is located near the thermostat, which allows you to record signals as accurately as possible, identifying signs of malfunction in a timely manner for the DTOZH.
Identifying Symptoms of Problems
Nothing lasts forever, half the moon, all devices fail, it's only a matter of time. If the sensor suddenly fails and the car owner does not pay attention to this fact, then a lot of problems may arise very soon.
The defect can usually be identified very easily, visually during routine inspection, but there are circumstances when special diagnostic devices are needed to measure the level of resistance and voltage of the electric current in the circuit.
In the event of a breakdown, the following problems occur:
– significantly more fuel is required;
– CO emissions increase;
– the engine may fail altogether;
– the car begins to obey the steering wheel poorly, which is fraught with an accident;
– the engine warms up slowly or, on the contrary, overheats.
The operation of the monitoring device is quite often affected by poor oxidation with glue, rust or moisture; all these nuances should be clarified and the sensor should be replaced urgently.
Replacement stage
It happens that the engine begins to “behave,” behave inappropriately, or simply suddenly stall. Replacing the engine is not a panacea at all, especially since the reason may not be in the engine at all.
The problem may be hidden in a broken sensor; you should first identify the signs of a malfunction of the coolant temperature sensor; simply replacing it often restores the status quo, and the engine can still serve for many years without failures.
conclusions
Most often, an experienced driver will notice that the sensor is broken; this does not even require special instruments to establish this fact.
The most important thing is not to put off resolving the matter indefinitely, but to take measures to solve the problem.
Remember: saving on the purchase of a sensor can lead to the engine failing sooner or later; it is better not to experiment and resolve all issues in a timely manner.
Source: http://bizovo.ru/articles/priznaki_neispravnosti_datchika_temperatury_ohlazhdayuschej_zhidkosti-17.html
How to check the coolant temperature sensor and identify its malfunction
The coolant temperature sensor, or, in short, DTOZH, is a device that determines the temperature of the antifreeze in the cooling system and gives a signal to lower it by triggering the fan.
Its performance is an important nuance of the normal functioning of the cooling system and the entire power unit as a whole, and therefore in this material we will talk about what specific indicators of a DTOZ malfunction help to recognize problems in its operation in a timely manner and effectively eliminate them.
Dtozh - what is that in the car?
The coolant temperature sensor in a car is a compact device located in the radiator housing or, often, in the outer part of the power unit housing - the so-called “jacket” of the cooling system.
Purpose
The sensor is designed to determine the temperature of the coolant, which is displayed on the information indicator located in the car's device panel.
In addition, the function of the sensor is to activate the cooling fan, which lowers the temperature of the antifreeze if it exceeds critical values (more than 80 degrees Celsius). This is done in order to avoid boiling of antifreeze and, as a result, overheating of the engine.
Video - nuances that are associated with coolant temperature sensors on the Volkswagen Passat B3:
A similar purpose of the sensor was typical for carburetor engines. Now, with the development of injection injection systems, a significantly larger number of functions are assigned to the DTOZH. These may include:
- increasing engine speed during the warm-up phase to optimize the engine’s output to operating mode;
- opening or closing the exhaust gas recirculation valve;
- setting the ignition timing, etc.
Principle of operation
The functioning of the DTOZH is carried out on the basis of the physical characteristics of the sensor material to change its own electrical resistance depending on the degree of heating.
In fact, it consists of two cone-shaped working and electrically conductive contacts of an element made of sensitive material. The change in the degree of electrical conductivity is recorded and, thus , the sensor “provides” data about the temperature and the achievement of its critical values.
On modern cars, the electronic control unit of the ECU is responsible for reading such information, which issues control commands for the ignition system and determines the functionality of the sensor itself.
Kinds
It is conditionally possible to distinguish two types of DTOZH: mechanical and digital. What are their differences and similarities?
Mechanical
Mechanical DTOZh is a simple unit where the transmission of information about the transformation of material resistance is carried out, so to speak, in “analog” form - using an electrical signal. This sensor is directly connected to the coolant temperature gauge, which is, in fact, a simple ohmmeter with a scale graduated in degrees Celsius.
A relay is connected to the node, which closes when the critical temperature is reached and causes the cooling fan to operate. Such sensors are seen on cars with carburetor engines, including all domestic Zhigulis.
Digital
Digital DTOZH in its design is not sharply different from mechanical, but the signal is transmitted using a bus specifically to the digital control unit of the ECU.
The built-in processor creates a primary analysis of information, displaying temperature information on the dashboard, and giving commands to the ignition system. In this case, is also turned on using a command from the ECU.
What does it affect?
The main task of the coolant temperature sensor is to turn on the cooling fan. As a result, if it malfunctions, the fan does not operate, and this may result in overheating of the motor or, at a minimum, boiling of antifreeze in the aggregate.
Video - how to check DTOZH with a multimeter:
In addition , on injection engines, a malfunction of the DTOZ leads to the fact that the ECU sets the wrong ignition timing, the engine increases and fuel consumption begins to work in negative conditions.
The combination of these factors shows that timely replacement of the sensor and identification of the sensor is the main element that allows you to avoid many troubles, and sometimes expensive repairs of the car engine.
signs of malfunction and main causes of the coolant temperature sensor
In most cases, due to the simplicity of the design, breakdowns of the coolant sensor itself are quite rare. However, there are a very large number of “pretexts” for it to start malfunctioning, and the following circumstances may be included among them:
1. Low quality antifreeze
When using bad antifreeze or domestic “Antifreeze”, there are often cases when the surface of the sensor is corroded or covered with crystalline sediment.
As a result, the temperature effect on the sensor changes and, as a result, its readings change, in most cases, towards a lower temperature.
This leads to untimely switching on of the cooling fan and transformation of the operating mode of the power unit.
2. Poor quality level of the sensor itself
Unfortunately, there are many counterfeit spare parts on the market, and DTOZH from a no-name manufacturer does not always meet factory parameters. In addition, the sensor may have minor damage, which during operation may contribute to its failure.
3. Antifreeze leaks through the sensor threaded connection
And, as a result, a change in its indicators. This phenomenon is seen when the integrity of the thread is violated in cases where the sensor was installed with excessive tightening or there is wear on the liner gasket.
4. Electrical failure
This factor is the main reason for the failure of the sensor and is possibly caused by a number of circumstances - from a sharp surge in voltage in the on-board electrical system of the car to simple corrosion of the contacts. In fact, diagnostics of contacts for the presence of oxidation should always be carried out when removing or installing the DTOZH.
5. Thermostat malfunction.
How to check the coolant temperature sensor
If you suspect a faulty DTS, you must first find out whether the breakdown concerns the sensor itself or whether it is due to failures in the electrical system of the car.
To do this, you need to unscrew the sensor and diagnose it. This can be done using a simple household multimeter.
How to check DTOZH with a multimeter
To measure the resistance of the DTOZH at different temperatures on the multimeter, turn on the ohmmeter mode with the appropriate measurement limit.
The resistance value must be in a certain range at specific temperatures.
For each power unit model and car brand, the sensor resistance at different fluid temperatures has personal values (!) and you should familiarize yourself with them in advance in the manual!
To check, remove the sensor and load it into water heated to a certain temperature by connecting a multimeter to the output contacts of the DTOZH. If the sensor resistance does not correspond to the values specified for your car's engine, it must be replaced.
Video - how to check the coolant temperature sensor using a multimeter and an electric kettle:
In addition, measurements can be created specifically on the car as the engine warms up at idle speed.
If the sensor is operational, you should look for the circumstances of the breakdown in the electrician or thermostat. If the DTOZH malfunctions, it should be replaced.
Replacement
The procedure for replacing the DTOZH is extremely simple and involves unscrewing the old sensor and installing a new one, followed by connecting the control terminals to it.
However, there are some nuances. In particular, the replacement should be combined with replacing the coolant in the car engine. Under such conditions, it is good to treat the mounting socket for the sensor with graphite lubricant, which will protect the thread, ensure easy unscrewing and create an additional layer of sealing.
Video - replacing the coolant temperature sensor on a VAZ 2115:
In addition, when replacing the sensor, you need to use small sandpaper to sand the electrical contacts suitable for it. If the DTOZH is working properly and you do not plan to change it, it is important to clean it as a preventive measure, including sanding its contacts to improve electrical conductivity.
Conclusion
As you can see, replacing and checking the DTOZh is a fairly simple procedure. It does not require special knowledge and skills, as well as special equipment (with the exception of the mentioned multimeter).
Don’t forget that timely replacement of a faulty coolant temperature sensor will help you avoid many troubles, including possible overheating of power unit .
See recommendations on how to lubricate battery terminals to prevent oxidation and use during seasonal maintenance of your own car.
What resistance should high-voltage wires have?
What are contract engines http://voditeliauto.ru/poleznaya-informaciya/dvigateli/chto-znachit-kontraktnyj.html and at a time when there is a point in taking them.
Video - how to check the coolant temperature gauge on a Chevrolet Lacetti:
Required reading:
Check the temperature sensor coolant
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Source: http://iru-cis.ru/kak-proverit-datchik-temperatury-ohlazhdajushhej/
Checking the VAZ DTOZH - diagnosing temperature sensor faults
Modern cars are equipped with all devices that facilitate monitoring the condition of the engine and its further diagnostics. It is impossible to talk about which sensor is more important and which is not. They all play an equally important role.
For example, DTOZH will help to detect engine overheating in time, and therefore save the driver from high costs associated with major engine repairs. Today you will learn how to diagnose the temperature sensor DTOZH VAZ 2114.
Symptoms of a faulty coolant sensor
First of all, it must be said that checking the sensor always begins with some reason. Firstly, the temperature gauge needle shows an overestimated value, which indicates a malfunction of the cooling system. The second, subsequent reason is the engine cooling fan not working.
The fact is that the sensor analyzes the coolant temperature and sends a corresponding signal to the engine controller, which turns on the fan. If it doesn't work, it makes sense to check it first. To do this, its chip is disconnected and connected directly to the battery. If it works, then the sensor is faulty.
Another sign is the lack of temperature information on the on-board computer or a signal that the engine has overheated. After this, it 100% makes sense to check the coolant temperature sensor.
Many drivers confuse two sensors - the temperature gauge sensor and the fan switch sensor. In fact, they are completely different, but with the same principle of operation.
How to check the DTOZH on a VAZ 2114 with your own hands
First of all, you need to remove the sensor. It is located near the cooling jacket pipe. To make removal easier, first remove the air filter. Don't forget to disconnect the negative terminal of the battery and drain the antifreeze from the cooling system. Otherwise, antifreeze or antifreeze will flow in a stream directly from the hole in the cooling jacket. Before dismantling, disconnect the sensor chip.
Using a 19 or 21 key, unscrew the DTOZH from the jacket. Now comes the fun part. Fill a small container with some antifreeze, and attach an ohmmeter or multitester with resistance measurement mode to the ends of the sensor. Now place this container on the gas stove and begin to slowly heat the antifreeze. For accurate measurements, install a thermometer in the container.
So, a working sensor should give the following readings at certain temperatures:
- 3520 Ohms at 20 degrees Celsius
- 667 Ohms at 60 degrees Celsius
- 177 Ohms at 100 Degrees Celsius
If there are any inconsistencies or discrepancies in the obtained values, you can immediately draw conclusions that the sensor is not working and needs to be replaced.
Otherwise, you risk stumbling upon a major engine overhaul, which will cost you much more than a new sensor. It is immediately worth noting that such a sensor is non-repairable.
If the readings are correct and the problem remains, then look for it elsewhere, for example in the controller software or thermostat.
That's all. As you can see, checking the sensor yourself is a simple task that will require a minimum of equipment and skills from you.
Source: http://VipWash.ru/sistema-ohlazhdeniya/proverka-dtozh-vaz-diagnostika-neispravnostey-datchika-temperatury
How to check the coolant temperature sensor, signs of sensor malfunction
The coolant temperature sensor is one of the most important parts in a car. It is she who is responsible for the engine temperature. Based on the data it collects, adjustments are made to the system to achieve the best performance with minimal energy costs.
The engine management system takes readings from a sensor that monitors the condition of the fluid in real time. Based on the data obtained, control changes in engine operation are implemented.
Based on the collected data, the control unit adjusts parameters such as:
- shaft rotation speed,
- ignition timing,
- composition of the fuel-air mixture.
Thanks to the temperature sensor, the engine warms up quickly with minimal energy consumption. Moreover, it guarantees optimal temperature inside the engine in all operating modes.
In modern cars, the sensor, which is designed to monitor the coolant, is an element of a complex electronic system. It allows you to continuously monitor the condition of the engine and, if necessary, make adjustments to its operation.
A little history
Initially, a thermal relay was installed in the car to control the temperature of antifreeze. Moreover, such a device was installed only on the engines of advanced cars.
In the design of the thermal relay, the contact is open, which means that the engine gradually heats up, but as soon as it is closed, the motor returns to its normal operating algorithm. At the same time, the temperature is kept in the optimal range.
Decades later, the design of the coolant sensor, which is responsible for its temperature, has changed dramatically, as has the operating principle. Now its role is played by an ordinary resistor that measures resistance.
In modern cars, temperature control is carried out constantly. As a result, productivity, safety and efficiency have increased significantly. Modern thermistors are made from cobalt oxide. Nickel can be used as an alternative.
The choice of such materials is explained extremely simply. These chemical compounds, when the state of the coolant changes towards an increase in temperature, release a huge number of free electrons. As a result, the resistance decreases several times.
In most engines, the thermistor placed in the coolant has a negative temperature coefficient. As a result, the highest resistance is achieved precisely when the engine is cold.
The voltage supplied to the sensor is 5V. Moreover, as soon as the resistance changes, the energy supply decreases. All changes are monitored by the control unit. It is on these indicators that the determination of the antifreeze temperature depends.
True, there are exceptions. For example, the French company Renault became famous for installing sensors on cars that had a positive temperature coefficient. As a result, the operating principle has changed slightly. Now, as the temperature increases, the resistance increases along with it.
Where is the coolant temperature sensor located?
Finding the sensor will not be difficult. It is located inside the case. It is on the latter that the thread responsible for fastening the device, which will be responsible for the temperature indicator of the coolant, is attached. There is also an electrical connector on the case.
Of course, a lot depends on the design of the car in which the coolant sensor is installed. But in most versions it is built into the exhaust pipe.
In the most advanced engine models, two sensors operate simultaneously. The task of one is to record the temperature of the coolant at the outlet, and the other at the inlet. In this way, it is possible to achieve the best performance and almost instantaneous response of the system.
The main thing in the location of the temperature sensor is that its tip is in contact with the coolant. As a result, the device can most often be found in the intake manifold near the thermostat housing. The second option is in the cylinder head.
Testing the temperature sensor
Symptoms of a problem
It is generally accepted that the sensor responsible for the temperature in the coolant rarely breaks down. This is true. Even reputable automotive experts believe that this is one of the most reliable parts in a car. It's all about its simplicity.
Maximum simplification of the design made it possible to achieve incredible operational reliability. However, even with it, problems can arise, and in order to identify them in time, you will need to show some care.
Usually all malfunctions come down to incorrect measurement of the coolant temperature. As a result, the resistance is broken, and the electronic unit begins to malfunction.
In order to prevent vehicle breakdown, you must always monitor its condition and make adjustments at the slightest deviation from the norm. Every driver must treat his vehicle with care. This will guarantee long service life.
The most common sign of a malfunction of the sensor, which is responsible for the temperature of the coolant, is the inactivity of the fan when the substance exceeds the degree limit. But this sign is not always reliable. The thing is that, as mentioned above, some systems have two sensors.
Sometimes car manufacturers assign tasks that are unusual for temperature sensors. For example, one device can monitor the temperature and transmit data to the control unit, while another can turn on the fan when a certain threshold is exceeded.
In most cases, fan failure indicates oxidation of the wiring. As mentioned above, the sensors themselves rarely break down. But this still happens.
If you have a car that was purchased in recent years and it has an on-board computer, then this device will indicate when the sensor that measures the fluid temperature has failed or become unstable.
But be careful! A message on a computer monitor does not always indicate a device malfunction. A break in the wiring can lead to the same message as, in fact, oxidation of the contacts.
An important indicator of a malfunction of the sensor that regulates the coolant temperature through the control unit is increased gasoline consumption. Increased speed is also observed when the engine is idling.
If the temperature sensor has any problems, then each time it will be more and more difficult for you to start the car even after warming up. Under the most unfavorable conditions, the power plant may fail due to overheating. As a result, the stability of the cylinder heads will be disrupted, and this can not only lead to extremely expensive repairs, but also cause an accident.
Checking the sensor
All the reasons described above can only be prerequisites for replacing or repairing the device. To determine the breakdown, you will probably need to conduct a much more thorough diagnosis.
As an example, let's look at how a VAZ-2110 is checked. First, disconnect the block and all wires from the sensor. To do this, you will need to squeeze out the plastic clip.
The diagnostic procedure itself is not very complicated. But before you start, check the integrity of the wiring to eliminate this cause of unstable operation.
During testing, the voltage will be at least 5 V. If the value is much lower, it means that the cause of the malfunction does not lie in the sensor, which is responsible for monitoring the temperature readings of the coolant.
In order to carry out diagnostics you will need the following devices:
Before removing the temperature sensor, drain some coolant. It is enough for the sensor to become half open. The chip must be disconnected using a key. Just unscrew it from its seat.
Diagnostics using an electric kettle allows you to quickly and without any difficulties determine the performance of the device. Also, when diagnosing, you will need a multimeter and a thermometer.
The verification procedure itself consists of the following steps:
- Immerse the part of the sensor that is responsible for measuring temperature into the electric kettle. The water should be cold.
- Place a thermometer in the kettle (the device must be electronic).
- Connect a multimeter to the sensor.
- Turn on the electric kettle.
- Measure the indicators.
If the device is in working condition, then at +15 there should be a resistance of 4450 ohms, at forty - 1459, at 95 - 177 ohms.
Results
The sensor responsible for the temperature regime of the coolant is an extremely reliable device. But even he sometimes fails. In this case, checking its functionality takes no more than half an hour.
Source: http://car-avz.ru/glavnaya/posobie/2010-kak-proverit-datchik-temperatury-okhlazhdayushchej-zhidkosti-priznaki-neispravnosti-datchika
Signs of a malfunction of the coolant temperature sensor, which is affected by its condition
Modern cars build their action algorithms based on the readings of various sensors. Most of these devices analyze some parameter and transmit information to the electronic control unit (ECU).
If, for example, there are signs of a malfunction of the coolant temperature sensor (DTOZH) or another tester, then such devices should be replaced. Incorrect information from them can cause malfunctions in the operation of the engine and other important vehicle systems. Let's look at the situation using the example of cooling a cylinder block.
When the engine is running, heat is generated in the car from the cylinder block. The coolant is responsible for removing excess heat. It circulates through the channels of the block, as well as in the radiator.
When understanding what the coolant temperature sensor affects, you need to understand how such a device works.
After all, its task is to send signals about the state of the engine, guided by indirect data (temperature).
The ECU is informed if the engine is cold, operating in standard temperature ranges, overheating occurs, or the internal combustion engine only reaches operating parameters after starting. Such data is analyzed by electronics, and on their basis the overall operation of the power plant control systems is formed.
By influencing the performance of this sensor, you can improve the car's controllability when driving on a cold engine, stabilize idle speed, and reduce the level of harmful emissions. Accordingly, a malfunction of the coolant temperature sensor or its transmission of distorted data to the control unit will create noticeable problems.
Thanks to the signals from this electronic device, automatic commands are generated for the following systems:
- Fuel enrichment process. If the head unit receives information about the low temperature of the cooling liquid, then the injection time for the injectors is recalculated upward. This action contributes to stable idle speed. Gradually, the temperature rises, and based on such readings, the injectors lean the mixture. If the sensor does not provide the correct information, then over-enrichment will occur, additional unnecessary costs for fuel emissions, and increased emissions pollution.
- Increasing speed during start. The engine may stall if the speed at startup is insufficient. A command from the ECU to accelerate the rotation so that the car does not stall helps get rid of this.
- Exhaust recirculation. To maintain controllability during the startup phase, the recirculation valve must be closed before the system reaches operating temperature. If you do not do this, you will get unstable speed or stalled car.
- Ignition angle. The setting of this parameter must be strictly regulated in order to reduce the amount of harmful exhaust before the temperature rises. The flow rate and output parameters of the power plant depend on the ignition advance/retardation.
- Condition of the filter that captures fuel vapors. It is necessary to purge the carbon filter only when the engine has completely warmed up.
- The torque converter clutch in the gearbox is not blocked until the engine warms up. This is done to ensure optimal controllability is maintained.
- Turn on the cooling fan. Based on data from the DTOZH, the cooling system fan is started or turned off. It helps to reduce the temperature of the refrigerant faster. In some car models, a separate sensor with a single function is used exclusively to start such a fan.
Types of coolant temperature sensors
Most often, a thermistor is used as a working tool for DTOZH. It is capable of changing the resistance in an electrical circuit when the temperature of the environment in which it is located changes. Typically, materials are used in which electrical resistance decreases as the fluid heats up.
How to unscrew the DTOZH
When it cools down, the resistance of the coolant temperature sensor increases significantly. Based on these readings, signals are generated that are sent to the ECU.
As an example, consider General Motors sensors. At a temperature of 0 C it has a resistance of 10 kOhm.
If the coolant warms up to approximately 93 C during engine operation, then the thermistor value drops to 0.2 kOhm. Ford's DTOZh at O C has a parameter of 95 kOhm.
When the power plant reaches operating temperature at 93 C, the resistance level reaches 2.3 kOhm.
From these readings it is clear that the characteristics for different car manufacturers are set individually. Therefore, when choosing a new sensor in a store, you need to take into account the car brand and specific model. Otherwise, the readings of the new device and its signals may differ significantly from those planned for a particular ECU.
You need to know that the temperature sensor meter for the coolant must directly touch the refrigerant.
The DTOZH is usually located in the intake manifold not far from the thermostat installed there. Less commonly, designers install this sensor closer to the cylinder head. With a V-shaped cylinder arrangement, engineers install a pair of DTOZH on each row of combustion chambers. A pair of sensors can also be installed separately for the fan and ECU.
For electronic readings to be accurate, there must be a normal level of refrigerant in the system. If there is insufficient coolant, the DTOZH operation may malfunction. Therefore, you need to add coolant to the system on time.
Detection of sensor inoperability and possible failures
Many systems rely on the readings of a temperature sensor, so its faulty operation entails a chain of erroneous automatic actions and incorrect operation of the motor. Such problems can quickly damage individual parts and entire units.
Checking the coolant temperature sensor
You need to know that most problems, as experience shows, are not related to the breakdown of the DTOZh or its internal problems, but to troubles with wiring or a rusted or leaky connection in the system.
One of the impact factors from the operation of a thermostat is the thermostat. Running the refrigerant constantly in a large circle, even on a cold engine, will not allow the engine to reach operating temperature for a long time. This will lead to additional fuel consumption, intensive wear of power plant parts, increased emissions and other problems.
When inspecting the DTOZ installation area, you can independently identify possible malfunctions.
You should worry about the following signs:
- presence of damage to the temperature sensor housing (cracks, chips, etc.);
- refrigerant leak (visible drips, presence of drops around the connection, dried drips sprinkled with dust);
- oxidation around the threaded connection (problems with unscrewing the sensor even a partial turn).
However, even with such defects, the electrical appliance may be in working condition. The reason may be a mismatch in its electrical output parameters.
You can check using a multimeter. The readings must be checked against the reference values for each car model. If a short circuit, incorrect output data or faulty contacts are detected, the device must be replaced.
When the test reveals the functionality of the sensor, the correct response to temperature fluctuations, but the motor continues to operate with an open circuit, not paying attention to signals from the DTOZH, then it is necessary to identify problems in the electronic control unit.
Two devices will help you monitor the output parameters:
You need to focus on a value of 3 V. When the motor warms up and the temperature increases, the voltage will drop to 1.3-0.5 V. On the oscilloscope, these values should be reached in 4-5 minutes.
When the testers show a voltage less than 5 V, this indicates a loss of reference voltage or a short circuit. Some sensors are equipped with a maximum/minimum function.
During testing, they will experience sudden voltage surges as the temperature rises.
On the obtained oscillogram data, shorted moments will appear as a drop to zero, and breaks in the circuit will be indicated by an increase in voltage to 5 V.
In the case when the output parameters of the DTOZH correspond to the norm, and the temperature in the system does not return to operating mode, the cause of the malfunction most likely lies in the thermostat. Its circuit remains in the open position, and the refrigerant does not heat up to the temperature set by the automaker.
Drivers rarely pay attention to this element of the system until the internal combustion engine begins to malfunction. Actions begin only after it breaks down.
However, it is recommended to change the DTOZ every time the engine is disassembled, because during operation the temperature sensor is subject to intense wear in aggressive conditions.
A worn-out device may produce incorrect or inaccurate signals. The only way to get rid of this is by replacing the device.
In addition to engine repair, it is recommended to change this electronic indicator along with the thermostat after significant engine overheating , during which both elements of the cooling system usually fail. When replacing, you need to drain the refrigerant to such an extent that its level drops below the sensor hole.
Simultaneously with replacing the sensor, the coolant is often updated . Its service life is usually about 3-5 years.
Contaminants dissolved in it can distort the transmitted data, and they also reduce the efficiency of the entire system. Before screwing, it is customary to lubricate the thread with sealant .
After installation, fill in new coolant .
Source: http://xn--b1altabgdr.org/avtoremont-i-tyuning/priznaki-neispravnosti-datchika-temperatury-oxlazhdayushhej-zhidkosti-na-chto-vliyaet-ego-sostoyanie
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